In recent years there has been great development of smart munitions, including cluster bombs which fire a plurality of submunitions or submunition grenades inside a single casing which opens over the target to release the submunitions within, and their increasing use around the world against a variety of targets. However, conventional submunition grenades have a number of disadvantages. The use of submunition grenades having a shaped charge and a simple inertial impact fuze is effective against armoured targets, but is is limited in its efficacy against area targets.
Conventional submunition grenades also suffer from undesirable initiation of fuzes due to collisions in air by submunition grenades, i.e., immediately after their expulsion. This lowers the reliability of the system, leads to loss of the submunition grenade, damages neighboring submunition grenades by the explosion, and creates duds.
Furthermore, the increasing use of submunition grenades creates a large quantity of duds which endanger friendly forces. These duds can be used by the enemy as booby traps, and call for substantial resources to clean the affected area, in order to permit its use by civilians. In addition, the heavy metals and other materials found in the batteries of many of the conventional submunition grenades' fuzes damages the ecology of the area in which they fall.
One solution to this problem is provided by Tari et al, in U.S. Pat. No. 5,387,257 which describes a self-destruct fuze for submunition grenades. The fuze includes an electrical self-destruct unit which is operative in the event that the mechanical primary inertial impact mode fails to operate upon striking an intended target. This fuze includes all the components for a conventional impact fuze, as well as an entirely separate electric self-destruct system. The fuze is relatively large, to accomodate the mechanical impact detonator and the battery. The fuze is problematic for several reasons: the batteries include heavy metals and other materials which damage the environment; the chemicals in the batteries age, but the batteries cannot be replaced since it is difficult to reach them in each grenade; the fuze includes a mechanical striker which, in the case of a dud, can be activated accidentally by friendly forces, or can be used to initiate the submunition grenade as a booby trap; the reserve battery in the fuze can be activated by transportation vibration, whereby there will be no electricity to initiate the detonator at the time of firing the submunition grenade in the case of a dud.